Circuit breaker having butt contacts



May 16, 1939. G. E. WHITEHEAD 2,153,920

CIRCUIT BREAKER HAVING BUTT CONTACTS Filed Sept. 18, 1956 INVENTOR GEORGE E- WHITEHEAD ATTORNEYS Patented May 16, 1939 UNITED STATES PATENT OFFICE CIRCUIT BREAKER HAVING BUTT CONTACTS George Ethelbert Whitehead, Cardiff, South Wales, assignor to Whitehead Switchgear and Inventions Limited,

Cardiff, South Wales, a

corporation of Great Britain 2 Claims.

This invention relates to electric switches and circuit breakers, and more particularly oil circuit breakers, and the invention specifically relates to switches and circuit breakers having butt 1 type contacts.

In switches or circuit breakers with butt type contacts, particularly when providing a plurality of breaks such as two breaks in series with the usual moving bridge arrangement, it is desirable in to introduce resiliency in order that reasonably good contact may be obtained and heretofore it has been the practice to provide the resiliency with that butt contact or those butt contacts which is or are carried by the moving member or 15 bridge. Thus the stem of the moving butt contact has been made slidable within its carrier or bridge and urged towards the fixed contact with which it co-operates, by means of a spring whilst electrical connection between the moving butt con- 0 tact and its carrier or bridge is usually effected by a flexible conductor or pigtail. It will be appreciated that the provision of the means giving the requisite resilience necessarily adds to the weight of the moving parts.

According to the present invention in an electric switch or circuit breaker of the butt contact type, whereas the moving butt contact is preferably rigidly carried on its support or bridge, the fixed butt contact is resiliently mounted on its w support.

To enable the invention to be clearly understood a preferred arrangement thereof will not be described with reference to the accompanying drawing in which Fig. i is a sectional elevation of the contacts of a circuit breaker;

Fig. 2 is a sectional plan on the line IIII of Fig. 1; and

Fig. 3 is a fragmentary horizontal section, on

/ an enlarged scale, taken on the line IIIIII in Fig. 1.

At I is shown one end of the moving bridge of a double-break oil circuit breaker, which bridge rigidly carries at each end a butt contact 2 in contra-distinction to the usual resilient arrangement as hereinbefore indicated. Said butt contact 2 co-operates with the fixed butt contact 3 of the circuit breaker, which contact 3 is carried at the lower end of the terminal stem 4 of {in the circuit breaker.

According to the present invention the fixed butt contact 3 is resiliently mounted with respect to the circuit breaker stem 4 and in the arrangement illustrated this resilient mounting is {11) achieved by providing the contact 3 with a rigid stem 5 which slides with good electrical contact within a resilient sleeve contact 6 which is pref erably a circularly laminated socket member in accordance with my Patent No. 2,032,241 granted February 25, 1936. The sleeve or socket member 6 is disposed in a housing flange at the end of a metal tube I which is rigidly carried with good electrical connection at the lower end of the terminal stem 4. As shown in Fig. 3, and as shown and described in detail in my aforesaid patent, the sleeve contact 6 comprises an annulus of closely packed thin flexible laminae 6, composed preferably of similarly bent strips of copper having their inner ends disposed in close relation and forming a resilient wall for engagement with the stem 5, a portion of the periphery of which is indicated by the dotted line 5*, to provide a good electrical contact therewith. The outer ends of these laminae abut against the surrounding wall 6 of a recess formed in the lower end of the tube 1. The laminae Ii may be separated by interposed similarly bent but relatively shorter laminae 6 of phosphor bronze or steel. Within the tube "I is housed the spring 8 which urges the fixed butt contact 3 in the downward direction and the extent of downward movement of this contact is limited by means of diametrically opposite slots 9 formed in the wall of the tube I and having engaged therein the cross pin I0 passing through the stem 5 of the contact.

In the arrangement illustrated the fixed contact of the circuit breaker including the sleeve member 6 and the tube 8, are located in a shrouded tube II of insulating material which is carried in perforations in transverse barriers I2 and I3, which are fixed within the oil tank of the circuit breaker. In order that the pressure set up in the tank on breaking circuit may be wholly or in part relieved, the housing for the sleeve member 6 is slightly smaller in diameter than the bore of the tube I I and is formed with one or more longitudinal grooves I4 through which the mixture of oil and are gases can escape.

In the arrangement illustrated furthermore, there is shown secured to the cross pin II! a valve in the form of a flanged member I5 which therefore moves with the butt contact 3 during the opening and closing of the circuit breaker. Said valve thus opens on the closing of the circuit breaker and vice versa, whereby the oil beneath the transverse barriers I2 and I3 is placed under pressure by reason of the generation of the arc gases, and such pressure will depend in part upon the diameter of the flanged member I5 which latter may be provided with a plurality of recesses l6 which are preferably staggered with respect to the recesses l4 aforesaid.

I claim:

1. A heavy current high speed oil circuit breaker comprising a terminal stem, a butt type main moving contact having a short stem, 2. carrier on which the stem of said moving contact is mounted rigidly, said carrier being movable longitudinally to close and open the circuit breaker, a similar butt fixed contact having a stem, a resilient sleeve contact in which the stem of said fixed contact is slidable longitudinally, a metal housing secured to the terminal stem of'the circuit breaker and at the end of which said sleeve contact is carried rigidly, a spring in said housing urging said fixed butt contact towards the moving butt contact, an insulating shrouding tube housing said metal housing but with a restricted longitudinal oil passage therebetween, a partition sealed across the oil tank of the circuit breaker carrying said shrouding tube, and a valve member associated with said metal housing and linked with said fixed butt contact so that when the circuit breaker is closed said oil passage is open, and said oil passage becomes substantially closed when the circuit breaker is opened.

2. A heavy current high speed oil circuit breaker comprising a terminal stem, a butt type main moving contact having a short stern, a carrier on which the stem of said moving contact is mounted rigidly, said carrier being movable longitudinally to close and open the circuit breaker, a similar butt fixed contact having a stem, a resilient sleeve contact in which the stem of said fixed contact is sliolable longitudinally, a metal housing secured to the terminal stem of the circuit breaker and at the end of which said sleeve contact is carrier rigidly, a spring in said housing urging said fixed butt contact towards'the moving butt contact, an insulating shrouding tube housing said metal housing but with a restricted longitudinal oil passage therebetween, a partition sealed across the oil tank of the circuit breaker and carrying said shrouding tube, and a valve member associated with said metal housing and linked with said fixed butt contact so that when the circuit breaker is closed said oil passage is open, and said oil passage becomes substantially closed when the circuit breaker is opened, said metal housing and said valve each having at least one longitudinal channel relatively staggered.

GEORGE ETHELBERT WHITEHEAD. 

